(CNN) -- An Army private suspected of leaking classified material, including videos and other documents, has been transferred from Kuwait to a Marine Corps brig in Quantico, Virginia.

Pfc. Bradley Manning, who served as an intelligence analyst in Iraq, was charged in June with eight violations of the U.S. Criminal Code and is the military's focus in the investigation into who leaked tens of thousands of documents to the website WikiLeaks.

Manning, 22, will remain in confinement as the Army continues an investigation to determine whether he should face the military equivalent of a trial over the charges, according to a statement released by the Army on Thursday.

He has not yet entered a plea, since there has not been a decision about whether he should face trial, Army Maj. Bryan Woods said. Military lawyers for Manning referred questions about him to Woods.

Manning, who had top-secret clearance as an intelligence analyst for the Army when he was stationed in Iraq, was charged in June with eight violations of the U.S. Criminal Code for allegedly illegally transferring classified data, reportedly including an earlier video that wound up on WikiLeaks.org.

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On Wednesday, a senior Pentagon official said that Manning was believed to have accessed a worldwide military classified Internet and e-mail system to download documents.

The Pentagon official, who did not want to be identified because of the ongoing criminal investigation, said investigators believe Manning logged into a system called the Secret Internet Protocol Router Network, which essentially provides military members who have appropriate security clearances access to classified e-mails and the military's classified Internet system.

Julian Assange, WikiLeaks founder, has declined to say where his whistle-blower website got about 91,000 U.S. documents about the war. About 76,000 of them were posted on the site Sunday in what has been called the biggest leak since the Pentagon Papers about the Vietnam War.

The documents are divided into more than 100 categories and touch on everything from the hunt for al Qaeda leader Osama bin Laden to Afghan civilian deaths resulting from U.S. military actions. Thousands of pages of reports document attacks on U.S. troops and their responses, relations between Americans in the field and their Afghan allies, intramural squabbles among Afghan civilians and security forces, and concerns about neighboring Pakistan's ties to the Taliban.

"Mr. Assange can say whatever he likes about the greater good he thinks he and his source are doing, but the truth is they might already have on their hands the blood of some young soldier or that of an Afghan family," Adm. Mike Mullen, chairman of the U.S. Joint Chiefs of Staff, said at a Pentagon news conference Thursday.

Secretary of Defense Robert Gates said the massive leak could endanger troops and jeopardize U.S. efforts.

"The battlefield consequences of the release of these documents are potentially severe and dangerous for our troops, our allies and Afghan partners, and may well damage our relationships and reputation in that key part of the world," he said. "Intelligence sources and methods, as well as military tactics, techniques and procedures will become known to our adversaries."

WikiLeaks responded to the remarks in a Twitter post early Friday: "Gates, who killed thousands in Iraq, Afg and Iran-Contra says we might have 'blood on our hands.'"

The organization's founder has said it held back thousands of documents in order to redact information that could put people at risk. But CNN's review of documents found instances of names of informants and those who cooperated against the Taliban, as well as names of suspected insurgents who were being watched.

CNN has not independently confirmed the authenticity of the documents, but neither the White House nor the Pentagon has denied that they are what WikiLeaks claims they are.